Andrej Tozon has a quick tip on making the ListBox items behave as disabled.
The data context of this ListBox is a ViewModel with the Lights property. Lights is a collection of five Light objects.
One property that the Light object exposes is the Brush property; it will simply point to a solid color brush of a red, yellow or green color, respectively. The Ellipse’s Fill property is bound to the Brush property as can observed in the above code.